Pancreatic granular cell tumor combined with carcinoma in situ.

A 58-year-old man was treated for a granular cell tumor (GCT) of the pancreas; a very rarely occurring tumor. The patient, who had been followed for 6 years due to alcoholic hepatitis, chronic pancreatitis and elevated carcinoembryonic antigen (CEA) levels from smoking, was admitted to our hospital for evaluation of back pain, diarrhea and constipation. The patient was diagnosed as having pancreatic head cancer using clinical imaging studies, and a pylorus-preserving pancreatico-duodenectomy was done. In the resected specimen, a white tumor measuring 13 mm in diameter was observed at the pancreatic head, and there was marked fibrous change surrounding the tumor. The microscopic appearance of the pancreas showed atrophy of acinar cells, fibrosis, and dilatation of the main pancreatic duct (MPD). Within the tumor were oval cells with low-grade atypia and an increased number of diffuse eosinophilic granules. Neither mitosis nor invasive findings were observed. Periodic acid-Schiff staining and immunohistochemical staining for the S-100 protein were positive, thus the tumor was diagnosed as a benign GCT. In addition, carcinoma in situ was found at the dilated MPD. Therefore, this patient was diagnosed as having GCT with carcinoma in situ of the pancreas. To the best of our knowledge, this is only the fourth case of GCT of the pancreas to be reported.